1. Field:
This invention relates to an improvement in an injection device as part of an assembly for administration of parenteral solutions and the like.
2. Prior Art:
It is a common occurrence in hospitals that during the administration of a parenteral solution to a patient, it becomes necessary that the patient receive a medicament by rapid infusion. The medicament can be introduced by syringe by injecting into a resealable injection device located adjacent the needle of the administration set. This device is commonly referred to as injection bulb. It is made of resilient, elastomeric material and is friction fitted to a generally rigid, plastic needle adapter at one end and to flexible tubing at the other end. The usual solvent sealing techniques which are preferred cannot be applied since the materials of the parts are too dissimilar chemically to bring about an effective seal. Consequently, the parts are held together only as a result of pressures of stressed end portions of the elastomeric member on the needle adapter and flexible tubing.
In certain instances an administration set is subjected to excessive pressures and as sometimes happens the injection bulb separates from either the needle adapter or the tubing resulting in an interruption of flow of fluid into the patient. U.S. Pat. No. 3,378,006 discloses an approach for increasing the resistance against separation. The approach involves providing a series of spaced, inwardly directed, semicircular ribs on the inner surface of the bore at each end portion of the injection bulb. These ribs provide engagement with the needle adapter and tubing at spaced intervals with small annular chambers being formed between the ribs. To assist in the engagement of the flexible tubing with the injection bulb, the tubing is rigidified by a rigid tubular insert. Although such a device is a considerable improvement over other injection bulbs, it requires the rigid insert in the tubing to give a greater degree of assurance that separation at this location does not occur at reasonable overpressures. This adds to the costs and difficulty of manufacture.